An endoscope is a surgical tool designed to be placed inside a body in order to provide a view of the interior portion of the body. In endoscopic surgery, the endoscope is placed in the body at the location at which it is necessary to perform a surgical procedure. Other surgical instruments are placed in the body at the surgical site. The surgeon views the surgical site through the endoscope in order to assess the interior portion of the body and to manipulate the other surgical instruments to perform the desired surgical procedure. The development of endoscopes and their companion surgical instruments has made it possible to perform minimally invasive surgery that eliminates the need to make a large incision in the patient to gain access to the surgical site. Instead, during endoscopic surgery, small openings, called portals, are formed. One advantage of performing endoscopic surgery is that since the portions of the body that are cut are reduced, the portions of the body that need to heal after the surgery are likewise reduced. Still another advantage of endoscopic surgery is that it exposes less of the interior tissue of the patient's body to the open environment. This minimal opening of the patient's body lessens the extent to which the patient's internal tissue and organs are open to infection.
During endoscopic surgery, the environment of the body cavity may pose problems relating to proper operation of the endoscope. For example, the body cavity may be characterized by high humidity and/or a high temperature relative to that of the operating theater. Accordingly, inserting a relatively cold endoscope into the body cavity may result in condensation in the form of fogging on the surface of the endoscope and in particular on the optical window located at the distal end thereof. Such condensation may impair the transmission of information into the endoscope and thereby reduce the usefulness of the endoscope for the duration of the condensation, potentially prolonging the duration of surgery.
Various solutions to the fogging problem have been proposed. Given that condensation is a consequence of introducing a relatively cool object into the body cavity, one potential solution involves raising the temperature of the endoscope prior to insertion into the body, as by warm towels or warm baths. Another possible solution is to coat the affected areas of the endoscope with fog-resistant coatings to reduce the adhesion of liquid particles to the endoscope. Further approaches are outlined in U.S. Pat. No. 4,279,246 entitled DEVICE FOR PREVENTING CLOUDING OF AN OBSERVING WINDOW, U.S. Pat. No. 5,605,532 entitled FOG-FREE ENDOSCOPE, U.S. Pat. No. 5,647,840 entitled ENDOSCOPE HAVING A DISTALLY HEATED DISTAL LENS, and U.S. Pat. No. 5,910,106 entitled METHOD AND APPARATUS FOR HEATING A SURGICAL INSTRUMENT, the entire contents of all of which are hereby incorporated herein by reference.
Certain terminology will be used in the following description for convenience in reference only, and will not be limiting. For example, the words “forwardly” and “distally” will refer to the direction toward the end of the arrangement which is closest to the patient, and the words “rearwardly” and “proximally” will refer to the direction away from the end of the arrangement which is furthest from the patient. Said terminology will include the words specifically mentioned, derivatives thereof, and words of similar import.